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关键词： incubation behavior   eggshell porosity   onset of incubation   hatching asynchrony   egg   House Wren   Troglodytes aedon   WATER-VAPOR CONDUCTANCE   HATCHING ASYNCHRONY   BROOD-REDUCTION   TREE SWALLOWS   SHELL THICKNESS   GAS-EXCHANGE   AVIAN EGG   BIRDS   SYNCHRONY   GROWTH  

摘要： In birds, the duration of egg incubation (the time from incubation onset to hatching) can affect multiple components of nest success, but what affects incubation duration? Previous studies suggest that incubation duration is affected by both parental behavior and components of the egg, which have yet to be determined. One egg component that may be related to incubation behavior and the time until hatching is eggshell porosity, which affects the exchange of metabolic gasses and water vapor across the shell and, thus, the speed of embryonic development and incubation duration. We tested whether eggshell porosity was associated with the timing of incubation onset by female House Wrens (Troglodytes aedon Vieillot, 1809), and whether porosity varied within clutches in a manner that might be associated with incubation periods and hatching patterns (i.e., synchronous vs. asynchronous hatching). Eggshell porosity was unrelated to the onset of maternal incubation and did not differ between early-and later-laid eggs within clutches, but differed significantly among females and covaried with egg size. We conclude that producing all eggshells of similar porosity within clutches, while adjusting incubation onset once most or all eggs are laid, provide facultative maternal control over variation in hatching patterns.

关键词： SYSTEM  

摘要： In order to improve the shift quality of a two-speed inverse automated manual transmission (I-AMT) of electric vehicle (EV), optimal control is used to generate the reference trajectories of the clutch slip speed and motor torque. The offline optimization results are fitted and used for online implementation. In order to compensate the disturbances and modeling errors, a proportional integral derivative (PID) controller is added to ensure the closed-loop control performance. The proposed controller is almost free of calibration effort, because the feedforward part of the proposed controller considered the simple but dominant system dynamics. Finally, the control algorithm is confirmed through large amounts of tests on a complete powertrain simulation model, and the designed controller can provide satisfactory performance even under large variation of vehicle mass and road grade.

关键词： TOLL-LIKE RECEPTORS   REGULATORY T-CELLS   ANTIGEN-PRESENTING CELLS   IMMUNE-COMPLEXES   IFN-ALPHA   PHASE-I   MONOCLONAL-ANTIBODY   DOUBLE-BLIND   PROMOTE   ACTIVATION  

摘要： Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease that is characterized by the generation of immune responses to various nuclear components. Impaired clearance of apoptotic cells and loss of tolerance to self-antigens are involved both in the initiation and in the propagation of the disease. Dendritic cells (DCs) are key factors in the balance between autoimmunity and tolerance and play a role linking innate and adaptive immunity. DCs, particularly plasmacytoid DCs (pDCs), are the main source of type I interferon (IFN) cytokines, which contribute to the immunopathogenesis of SLE. There is accumulating evidence that pDCs and type I IFN cytokines take the leading part in the development of SLE. In this review, we discuss recent data regarding the role of pDCs and type I IFN cytokines in the pathogenesis of SLE and the potential for employing therapies targeting against aberrant regulation of the pDC-type I IFN axis for treating SLE.

关键词： Cyclades   Island biogeography   Island syndrome   Kotschyi's gecko   Life history   Reproduction   Mediodactylus kotschyi   LIFE-HISTORY TRAITS   GULF-OF-CALIFORNIA   ISLAND SYNDROME   MARINE SUBSIDIES   R-SELECTION   POPULATION   GEKKONIDAE   REPRODUCTION   LACERTIDAE   EVOLUTION  

摘要： The island syndrome describes the evolution of slow life history traits in insular environments. Animals are thought to evolve smaller clutches of larger offspring on islands in response to release from predation pressure and interspecific competition, and the resulting increases in population density and intraspecific competition. These forces become more pronounced with diminishing island size, and life histories are thus expected to become slowest on small, isolated islands. We measured clutch sizes in 12 insular populations of Mediodactylus kotschyi, a small gecko from the Cyclades Archipelago, a set of land-bridge islands in the Aegean Sea (Greece). We analyse variation in clutch size in relation to island area, island age, maternal body size, the presence of putative competitors and nesting seabirds (which increase resource abundance in the form of marine subsidies), and richness of predators. Clutch size of M. kotschyi decreases with increasing island area, in departure from classic island syndrome predictions, suggesting the evolution of faster life histories on smaller islands. There are no relationships between clutch size and island age, maternal size, the presence of competitors or predator richness. Instead, larger clutches on small islands could simply reflect the beneficial effect of marine subsidies derived from resident seabird colonies. Indeed, populations of M. kotschyi on islands with nesting seabirds have clutch sizes 30.9 % larger (1.82 vs. 1.39 eggs) than populations on islands without nesting seabirds. Thus, our data suggest that bottom-up effects of marine subsidies may supersede the expression of a simple island syndrome in the Aegean M. kotschyi.

关键词： Toxoplasma gondii   centrosome   apicomplexa   endodyogeny   schizogony   TOXOPLASMA-GONDII   KINASE   TACHYZOITE   DIVISION  

摘要： The centrosome serves as a central hub coordinating multiple cellular events in eukaryotes. A recent study in Toxoplasma gondii revealed a unique bipartite structure of the centrosome, which coordinates the nuclear cycle (S-phase and mitosis) and budding cycle (cytokinesis) of the parasite, and deciphers the principle behind flexible apicomplexan cell division modes.

关键词： Dual clutch transmission   backlash   engine harmonics   powertrain   shift transient   NOISE   IDENTIFICATION   SIMULATION   DYNAMICS  

摘要： The purpose of this paper is to numerically investigate the influence of nonlinearities applied to vehicle powertrains equipped with a dual clutch transmission, including gear backlash, dual mass flywheel hysteresis, and torque pulses from the engine. To achieve this goal, a multi-body dynamic model of such a powertrain is constructed for transient vibration studies. Incorporated into this model is a combination of two nonlinear contact backlash models: for gear pairs a line-of-action force contact model is used to represent backlash in the mesh, and, for engaged synchronizer dog gears, a torsional nonlinear contact model is applied. This powertrain model is then used to study the response to shift transients under different conditions, including with and without engine torque harmonics, the variation of mesh damping and tooth clearance, and the impact of torsional vibration absorbers. Simulation results demonstrate that engine torque harmonics, mesh clearance, and external damping sources have a significant impact on duration of excitation, while the impact of mesh damping is less significant.

关键词： 二分支   集总质量法   啮合偏差   时变啮合刚度   分扭角度   动载系数   均载系数  

摘要： 采用集总质量法建立二分支斜齿轮传动系统的动力学模型及动力学方程,考虑轮齿啮合偏差和时变啮合刚度等激励因素,研究分别在不同支承刚度和不同分扭角度情况下,传动系统的动载系数和均载系数的变化规律,得出如下结论:1较大的支承刚度有利于改善传动系统的均载特性和运转平稳性,在16倍初始支承刚度下系统的均载特性已趋近于理想情况;2二分支斜齿轮传动系统的分扭角度对其动载系数和均载系数有较大影响,在分扭角度为110°时系统的均载特性最优;3即使1μm的轮齿啮合偏差也会对系统的均载特性产生较大不良影响,应严格控制.

关键词： 超越弹簧离合器   预压缩量   自激   有限元方法  

摘要： 弹簧离合器是通过弹簧两端激发圈在壳体内预压缩产生摩擦力矩实现自激的,弹簧两端激发圈预压缩量的大小直接影响离合器的结合性能及使用寿命。运用有限元方法建立了弹簧离合器动力学模型,求解了不同端部预紧量下高速弹簧离合器输出壳体与输入壳体速度的同步性,以及弹簧的Mises应力和径向位移,由此得到了弹簧离合器自激接合的弹簧预压缩量条件,并与解析求解得到的离合器临界预压缩量进行了对比。此外,有限元分析结果表明,稳态接合后弹簧的应力分布呈M型,弹簧的过渡线圈段应力出现峰值,而中间端应力分布均匀。该分析可为弹簧离合器的优化设计提供依据。

关键词： 启动困难现象   发动机启动   离合器故障   离合器踏板   曲轴转动   故障现象   8G型   起动机  

摘要： 故障现象：一辆东风EQ1118G型汽车．当踩下离合器踏板时，出现发动机启动困难现象。尤其是热车时踩下离合器踏板，更是无法将发动机启动，起动机运转无力，甚至不能转动。此时若用手盘车（转动曲轴），会感觉到曲轴转动非常吃力，甚至不能转动。但松开离合器踏板后，